Surface plasmon resonance or (SPR) is a technique which can be used in the analysis of antibodies which are deposited on surfaces which have been coated with thin films of metal, in particular thin films of silver. SPR based sensors are discussed in a paper by I. Faulkner, W. R. Flavell, J. Davies, R. F. Sunderland and C. S. Nunnerly: "SPR-based sensors studied by electron energy loss spectroscopy and attenuated total reflection", to be published in J. Electron Spectroscopy, 1993. The manner in which a coating is applied to a surface has important consequences for the subsequent properties of that surface in terms of SPR and control of the coating process is important. At present, coating is generally performed by spattering but control is not good. It is important that the films are formed from uniform layers of metal in order to get reproducible SPR. On account of this, improved method for the production of films for SPR are desirable.
In a known process, a film of silver is deposited on a surface which has been subjected to a pretreatment comprising a number of steps including a step in which a preparatory metallic layer comprising titanium or chromium is deposited on a surface to form a base for the silver layer.